Synthesis and Characterization of Bacterial Cellulose from Citrus-Based Sustainable Resources

Citrus juices from whole oranges and grapefruits (discarded from open market) and aqueous extracts from citrus processing waste (mainly peels) were used for bacterial cellulose production by Komagataeibacter sucrofermentans DSM 15973. Grapefruit and orange juices yielded higher bacterial cellulose concentration (6.7 and 6.1 g/L, respectively) than lemon, grapefruit, and orange peels aqueous extracts (5.2, 5.0, and 2.9 g/L, respectively). Compared to the cellulosic fraction isolated from depectinated orange peel, bacterial cellulose produced from orange peel aqueous extract presented improved water-holding capacity (26.5 g water/g, 3-fold higher), degree of polymerization (up to 6-fold higher), and crystallinity index (35-86% depending on the method used). The presence of absorption bands at 3240 and 3270 cm-1 in the IR spectrum of bacterial cellulose indicated that the bacterial strain K. sucrofermentans synthesizes both Iα and Iβ cellulose types, whereas the signals in the 13C NMR spectrum demonstrated that Iα cellulose is the dominant type

Nitrogen and phosphorus in coastal sediments covered by cyanobacteria mats

Background. Biocommunities of phototrophic microorganisms (principally cyanobacteria) developing on the surface sediments of shallow, warm and semi-isolated coastal environments, bind or trap small particles on their polysaccharide sheaths creating organosedimentary structures. Those structures are called algal mats and they are commonly flat and laminar in shape. They are also called recent stromatolites due to their remarkable similarity to the fossil ones. Objectives. Not many geochemi cal studies exist concerning cyanobacterial mats in Mediterranean coasts, in comparison with the biological ones. Considering the importance of nitrogen and phosphorus in the cyanobacteria mat development, the present study aims to contribute to the knowledge of their chemical behaviour in such environments. Methods. Sediment cores of about 10 cm length along with water samples were collected during the course of a year from two Greek coastal areas. Sediments were fractionated in three distinct layers according to their structure. A wet oxidation method for the simultaneous determination of total nitrogen and total phosphorus was applied to all sediment samples. The total organic carbon (TOC), the total inorganic phosphorus and the natural pigment content in the sediment samples were also determined. Standard spectrophotometric methods were used for the determination of the concentration of dissolved nutrients. In situ measurements of pH, temperature and salinity were also carried out. Results and Discussion. The sampling areas were found to be in the mesotrophic level. The group of aerobic filamentous cyanobacteria dominated the sediment biocommunities. The pH of the sediment showed a gradual reduction downwards. The highest content of TOC, total nitrogen and total phosphorus were detected in the surface layer of the sediment samples. The contribution of organic phosphorus to the total phosphorous ranged between 0% and 50% with an average value of 26.6%. A depletion of organic phosphorus in the anoxic middle layer of the sediment was detected. A good positive correlation between total nitrogen and chlorophyll-a, as well as total nitrogen and TOC in the surface sediment layer, was observed. A good negative correlation between total phosphorous in sediments and dissolved phosphates in seawater was also observed. Conclusions. The high content of total nitrogen recorded in t he surface sediments indicate that cyanobacteria accumulate nitrogen acquiring it from the sediment, the marine environment and the air (in the form of N2). A proportional accumulation in phosphorus also happens, although to a lesser degree. The temporal fluctuation of nitrogen content in the sediment's surface layer agrees with the temporal fluctuation of primary production. The cyanobacterial mat acts as a natural pump that transfers phosphorus from seawater to the surface of the sediment. Recommendations and Outlook. A further, more extensive, multidisciplinary study of cyanobacterial mats is needed for the determination of the biogeochemical processes that take place there and for the effective environmental management of the areas where these forms develop. © 2006 ecomed publishers (Verlagsgruppe Hüthig Jehle Rehm GmbH), D-86899 Landsberg and Tokyo

Water quality in a Mediterranean marine protected area (North Sporades Islands, Greece)

Pollution in the marine protected area of North Sporades Islands was investigated in July 1997. Salinity, temperature, dissolved oxygen, dissolved inorganic nutrients, organic carbon, hydrocarbons as well as dissolved and particulate trace metals were determined at 15 offshore and coastal stations. Dissolved organic carbon and inorganic nutrient concentrations indicate the mesotrophic character of the investigated waters. The dissolved forms of nitrogen were slightly higher at coastal stations. Dissolved and particulate Cu, Zn and Ni, were higher in coastal stations, whereas concentrations of Pb were generally low and likely of atmospheric origin. Dissolved/Dispersed petroleum hydrocarbons (DDPH) were close to detection limits at all stations. Temperature and salinity vertical profiles, nutrient and trace metal concentrations revealed the presence of a slight influence of the Black Sea water coming from Dardanelles straits

Water quality in a Mediterranean marine protected area (North Sporades Islands, Greece)

Pollution in the marine protected area of North Sporades Islands was investigated in July 1997. Salinity, temperature, dissolved oxygen, dissolved inorganic nutrients, organic carbon, hydrocarbons as well as dissolved and particulate trace metals were determined at 15 offshore and coastal stations. Dissolved organic carbon and inorganic nutrient concentrations indicate the mesotrophic character of the investigated waters. The dissolved forms of nitrogen were slightly higher at coastal stations. Dissolved and particulate Cu, Zn and Ni, were higher in coastal stations, whereas concentrations of Pb were generally low and likely of atmospheric origin. Dissolved/Dispersed petroleum hydrocarbons (DDPH) were close to detection limits at all stations. Temperature and salinity vertical profiles, nutrient and trace metal concentrations revealed the presence of a slight influence of the Black Sea water coming from Dardanelles straits

The chemical behaviour of trace metals in a small, enclosed and shallow bay on the coast of Attika, Greece

A lot of small and shallow bays that exist along the extended Greek coastline differ significantly from the open sea in the fluctuation of hydrological parameters, the degree of eutrophication and the concentration of pollutants. These characteristics can sometimes create environmental conditions that favour the development of specific ecosystems like the algae mats. The chemical behaviour of dissolved and particulate forms of the most interesting, from the environmental point of view, trace metals along with the variations of salinity and temperature as well as the eutrophication degree in a bay near Athens, Greece was studied in this paper for the period of 1 year (July 2000-June 2001). The results of this study showed that the waters inside the bay are of a higher eutrophication level than the neighbouring open Saronikos gulf. In most cases, the cove's water is enriched in both dissolved and particulate metals in comparison to the neighbouring coastal area and the various parts of Saronikos gulf. The low rate of water renewal, the increased particulate matter, the algal mat and certain human activities (mainly during the warm period of the year) are the main reasons. A good correlation between the fluctuations of the concentrations of some metals inside and outside the cove also occurs. It indicates the contact between the area's water masses and the need for environmental planning covering a wide area around the system. © 2007 Elsevier B.V. All rights reserved

Time of blood pressure in target range in acute ischemic stroke

Objective: The purpose of this study was to investigate the association of blood pressure (BP) time-in-target range (TTR) derived from 24-h ambulatory BP monitoring (ABPM) during the acute phase of ischemic stroke (AIS), with the severity of stroke and its predictive value for the 3 months outcome. Methods: A total of 228 AIS patients (prospective multicenter follow-up study) underwent ABPM every 20 min within 48 h from stroke onset using an automated oscillometric device. Clinical and laboratory findings were recorded. Mean BP parameters, BP variability and TTR for SBP (90 – 140 mmHg), DBP (60 – 90 mmHg), and mean arterial pressure (MAP) were calculated. Endpoints were death and disability/death at 3 months. Results: A total of 14 942 BP measurements were recorded (~66 per AIS patient) within 72 h of stroke onset. Patient’s 24-h TTR was 34.7 ± 29.9, 64.3 ± 24.2, and 55.3 ± 29.4% for SBP, DBP and MAP, respectively. In patients without prior hypertension, TTR was lower as stroke severity increased for both DBP (P = 0.031) and MAP (P = 0.016). In 175 patients without prior disability, increase in TTR of DBP and MAP associated significantly with a decreased risk of disability/death (hazard ratio 0.96, 95% CI 0.95 – 0.99, P = 0.007 and hazard ratio 0.97, 95% CI 0.96 – 0.99, P = 0.007). TTR of SBP in 130 – 180 mmHg and 110 – 160 mmHg ranges seems to be related with mortality and disability outcomes, respectively. Conclusion: TTR can be included for a more detailed description of BP course, according to stroke severity, and for the evaluation of BP predictive role, in addition to mean BP values, derived from ABPM during the acute phase of AIS. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved

Integrated chemical and biochemical technology to produce biogas with a reduced ammonia content from municipal biowaste. Validating lab-scale research in a real operational environment

The current paper reports the scientific, technical, environmental, economic and social impacts of two integrated chemical and biochemical processes that employed a novel virtuous biowaste cycle under real operational conditions of three industrial sites in Italy, Greece and Cyprus. The work was based on previous laboratory research pertinent to the valorisation of municipal biowastes (MBWs) as a feedstock to obtain value added soluble biobased (SBO) products. The research pointed out that the site-specific nature of MBW was the main criticality, which could potentially hinder the industrialisation of the MBW-SBO paradigm. The present work demonstrates the feasibility of a new scenario for a conventional waste treatment plan collecting and processing MBWs by anaerobic and aerobic fermentation. In essence, the virtuous biowaste cycle is realised by producing SBO from the plant MBW (process 1) and recirculating it to the MBW feed of the anaerobic fermentation reactor to reduce the ammonia content in the digestate (process 2). This mitigates the digestate's environmental impact. Life cycle sustainability assessment demonstrates that the use of SBO produced from local MBW allowed reducing the ammonia content of the digestate generated from the local anaerobic fermentation facilities in the three different countries by 21–68% as well its eutrophication potential. Process 2 allowed at least 86% OPEX cost saving compared to conventional digestate post-treatment technologies for ammonia abatement, while paying off the CAPEX cost in less than one year. Socio-economic analysis evaluated the impacts on workers and local community stakeholders, potentially stemming from the implementation of processes 1 and 2 at European level. The analysis of SBO composition and performances in each operational site investigated showed that improved performance of process 2 might be achieved by isolating the active principles in raw SBO prior to their use in process 2. Chemical and biochemical catalysis by SBO active principles in process 2 support the specific perspective

Evolution in a family of chelatases facilitated by the introduction of active site asymmetry and protein oligomerization

The class II chelatases associated with heme, siroheme, and cobalamin biosynthesis are structurally related enzymes that insert a specific metal ion (Fe2+ or Co2+) into the center of a modified tetrapyrrole (protoporphyrin or sirohydrochlorin). The structures of two related class II enzymes, CbiXS from Archaeoglobus fulgidus and CbiK from Salmonella enterica, that are responsible for the insertion of cobalt along the cobalamin biosynthesis pathway are presented in complex with their metallated product. A further structure of a CbiK from Desulfovibrio vulgaris Hildenborough reveals how cobalt is bound at the active site. The crystal structures show that the binding of sirohydrochlorin is distinctly different to porphyrin binding in the protoporphyrin ferrochelatases and provide a molecular overview of the mechanism of chelation. The structures also give insights into the evolution of chelatase form and function. Finally, the structure of a periplasmic form of Desulfovibrio vulgaris Hildenborough CbiK reveals a novel tetrameric arrangement of its subunits that are stabilized by the presence of a heme b cofactor. Whereas retaining colbaltochelatase activity, this protein has acquired a central cavity with the potential to chaperone or transport metals across the periplasmic space, thereby evolving a new use for an ancient protein subunit